This is a claim typically put forth by gun rights supporters in favor of looser gun restrictions. Essentially, the argument goes like this: Law-abiding citizens will, by definition, respect the law, so if some or all guns are illegal, they will not purchase them. By contrast, many criminals will, by definition, ignore gun laws, acquiring guns illegally. This would shift the balance of power in favor of criminals. So to level the playing field, there should be fewer restrictions on firearms.
If this statement is mostly false, then many gun rights supporters have a lot of explaining to do. It would mean that the claim is, for all intents and purposes, a lie and an instance of fear-mongering. And it would need to stop right away. Because suddenly, gun control supporters would have a much stronger case for restricting who can buy firearms and what kind of firearms can be purchased.
However, if this statement is mostly true, then that can mean only one thing: There is a large underground market for guns in the US, possibly on the same scale as the drug market. If so, I ask the question: What does it look like? How are all these guns getting onto the black market? Are they smuggled from abroad, are they made right here in the US--legally or illegally--or is it a little bit of both? All of these questions would have to be thoroughly answered before we can discuss remedies.
What do you think about this, and what is the evidence for your claim?